Re: How to setup Jumbo Frames? NetBSD Dom0 and FreeBSD XENHVM

["Mike C." <miguelmclara%gmail.com@localhost>]

On 06/27/13 19:23, John Nemeth wrote:
> On Jun 27,  3:21pm, "Mike C." wrote:
> } On 06/27/13 07:43, Manuel Bouyer wrote:
> } > On Thu, Jun 27, 2013 at 04:47:10AM +0000, Mike C. wrote:
> } >>
> } >> First, sorry if I'm asking something basic.
> } >>
> } >> I have a re1 interface that supports jumbo frames (MTU up to 7422), the
> } >> card is set up correct, however I need a bridge for xen!
> } >>
> } >> When I try to change the bridge mtu settings:
> } >> # ifconfig bridge0 mtu 7422
> } >> ifconfig: SIOCSIFMTU: Network dropped connection on reset
> } >>
> } >> However ifconfig shows the mtu at 7422:
> } >> # ifconfig bridge0                                                       
>  
> } >> bridge0: flags=0 mtu 7422
> } >>
> } >> And the biggest problem comes when I try t start a domu... if the
> } >> bridge0 interface has a mtu different than 1500 I can't start the domu,
> } >> because the virtual interface creation fails with:
> } >>
> } >> brconfig: add xvif5i0: Invalid argument
> } > I guess you could change the /usr/pkg/etc/xen/scripts/vif-bridge
> } > script to set the mtu of the xvif before adding it to the bridge.
> } >
> } > But I'm not sure that the netfront/netback (at last as implemented
> } > on NetBSD) supports MTU larger than 4k.
> } 
> } Forgot to mention I tried that...
> } 
> } While staring the domU I see
> } ifconfig xvif5i0 up
> } ifconfig: SIOCSIFMTU: Invalid argument
> } ifconfig: SIOCSIFMTU: Network dropped connection on reset (this is for
> } the bridge)
> } 
> } If I set the script to set the MTU to any value other than 1500 thats
> } what I get!
> } 
> } I tried 9000 last night and today with 4000, has you can see the bridge
> } mtu changes even though I see the "Network dropped connection on reset
> } message"
> } 
> } ---> bridge0: flags=41<UP,RUNNING> mtu 4000
> } 
> } I was under the impression that since Xen 4.1+ mtu of 9000 are
> } supported, at least I according to the change log it should:
> } "Fixes to properly support jumbo frames (mtu 9000) with vif-bridge script."
> } 
> } But perhaps NetBSD needs some specific patch for this...
> } 
> } NOTE: I'm running 4.2.2 compile from source following the instructions
> } at: http://wiki.xen.org/wiki/Compiling_Xen_From_Source_on_NetBSD.
>
>      Xen 4.2 is in pkgsrc and you would probably be better off with
> it.  It fixes a whole lot of problems and adds functionality.
>
>      However, your problem sounds like it could possibly be with
> the backend driver in the kernel.  Certainly, it is something that
> is going to need significant investigation.
>
> }-- End of excerpt from "Mike C."
Ok pkgsrc version installed, I tried to add "mtu" in the vif-bridge script

Still I got:
ifconfig: SIOCSIFMTU: Invalid argument

However it still creates my DomU while before it didn't...
Daemon running with PID 1443
   

I tried to manually change it... no luck either!
# ifconfig xvif1i0 mtu 1500  (works)
# ifconfig xvif1i0 mtu 9000
ifconfig: SIOCSIFMTU: Invalid argument
# ifconfig xvif1i0 mtu 4000
ifconfig: SIOCSIFMTU: Invalid argument
# ifconfig xvif1i0 mtu 2000
ifconfig: SIOCSIFMTU: Invalid argument
# ifconfig xvif1i0 mtu 1400 (works)

So I guess it won't support mtu's superior to 1500

But this seams to be specific to NetBSD, If I understand right this
means some changes would be needed in netfront/netback... but should it
allow at least 4k?